Not exactly re: tax exemptions. Clinton did away with that and you’re taxed on the money before hand. But I’m not going to argue the fine points of it.
Contributions to most qualified retirement plans are not tax-exempt, they are tax-deferred. When you make a qualified contribution to one of those plans, you don't have to include the amount of the contribution in your taxable income for that year. That has been in place under the U.S. tax code since the 1970s, and it remains so to this day.
What changed during the Clinton administration was the introduction of a new kind of retirement plan where the contributions were not tax-deferred, but the withdrawals in retirement were tax-exempt. That's what the Roth IRA is.